1. Field
The present application relates to the field of directory services. More particularly, the present application relates to the application of electronic directory services, e.g., X.500 or LDAP, in relational databases, to table structures in database arrangements used for searching, and to methods for searching databases.
2. Description of the Related Art
A Relational Database Management System (RDBMS) provides facilities for applications to store and manipulate data. Amongst the many features that an RBDMS offers are data integrity, consistency, concurrency, indexing mechanisms, query optimisation, recovery, roll-back, security. RBDMS also provide many tools for performance tuning, import/export, backup, auditing and application development.
RDBMS are the preferred choice of most large scale managers of data. RDBMS are readily available and known to be reliable and contain many useful management tools. There is a large base of RDBMS installations and therefore a large amount of existing expertise and investment in people and procedures to run these systems, and so data managers are looking to use this when acquiring new systems. Most relational database products support the industry standard SQL (Structured Query Language).
There has also been a move towards Object Oriented systems, which provide data extensibility and the ability to handle arbitrarily complex data items. In addition, many corporations and governmental departments have a large number of database applications, which are not interconnected. Data managers are looking for solutions which enable them to integrate their data, and to simplify the management of that data. Electronic directories provide data managers with a tool to achieve these objectives. Some electronic directories are standardized. X.500 is the International Standard for Electronic Directories [CCITT89 or ITU93]. These standards define the services, protocols and information model of a very flexible and general purpose directory. X.500 is applicable to information systems where the data is fairly static (e.g. telephone directory) but may need to be distributed (e.g. across organisations or countries), extensible (e.g. store names, addresses, job titles, devices etc.), object oriented (i.e. to enforce rules on the data) and/or accessed remotely. Electronic directories, such as X.500 and its associated standards, provide a framework and a degree of functionality that enables data managers to achieve their objectives.
Typically, data managers prefer to implement an electronic directory, e.g., an X.500 directory, with all the flexibility of object-oriented systems, but using an SQL product so that the system can achieve the scalability and performance inherent in relational systems coupled with the stability, robustness, portability and cost-effectiveness of current SQL products.
One example of an electronic directory implementation is described in U.S. Ser. No. 09/427,267 and its corresponding Australian Patent 712451 both of which are incorporated herein in their entirety by reference. In the search strategies for this implementation, at a conceptual level, hierarchy tables, e.g., NAME, DIT and TREE, are used to maintain relationships between objects in a hierarchy. These hierarchy tables are arranged according to one row per object. Object tables, e.g., SEARCH and ENTRY, manage values within an object. These object tables are arranged according to one row per value. Every object has a corresponding row in the hierarchy tables and every attribute value has a corresponding row in the object tables. In this implementation, the object table used for searching objects contains rows of the form (EID, AID, VID, Norm), where EID identifies the object to which the value belongs, AID identifies the attribute type of the value, VID identifies one of a possible number of attribute values in the one entry, and Norm contains the syntax normalized value. Attribute tables, e.g., attribute, define information about attribute types. The attribute table used contains rows of the form (AID, SYX, DESC, OBJECT ID).
It has been discovered that improvements to electronic directory implementations may be achieved for arranging and searching databases for complex data types.